package org.ambari.hdfs.study;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;
import java.util.StringTokenizer;

public class WordCount {
    //编写TokenizerMapper类继承Mapper类
    public static class TokenizerMapper extends Mapper<Object,Text,Text,IntWritable>{
        public static final IntWritable one=new IntWritable(1);
        private Text word=new Text();
        @Override
        public void map(Object key, Text values, Context context) throws IOException, InterruptedException {
            StringTokenizer str=new StringTokenizer(values.toString());
            while(str.hasMoreTokens()){
                word.set(str.nextToken());
                context.write(word,one);
            }
        }
    }
    public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable>{
        private IntWritable result=new IntWritable();
        @Override
        public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
            int sum=0;
            for (IntWritable val:values) {
                sum+=val.get();
            }
            result.set(sum);
            context.write(key,result);
        }
    }
    //编写主函数
    public static void main(String[] args) throws Exception{
        Configuration conf=new Configuration();
        Path inpath = new Path("/user/lanwon/test/words.txt");
        Path outpath = new Path("/user/lanwon/test/wordscount001.txt");
        System.setProperty("HADOOP_USER_NAME", "root");
        Job job= Job.getInstance(conf,"wordCount");
        job.setJarByClass(WordCount.class);
        job.setMapperClass(TokenizerMapper.class);
        job.setCombinerClass(IntSumReducer.class);
        job.setReducerClass(IntSumReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        FileInputFormat.addInputPath(job, inpath);
        FileOutputFormat.setOutputPath(job, outpath);
        System.exit(job.waitForCompletion(true)?0:1);
    }

}
